Isolation and quantitation of phosphatidylcholine by reversed-phase liquid-liquid extraction

A simple and rapid method is described for the determination of total phosphatidylcholines in serum. Extracts of lipids are applied to octadecyl silica cartridges and phosphatidylcholines are eluted by methanol-acetonitrile mixtures containing choline. Quantitation of these compounds is performed by colorimetry of their complexes with erythrosin B. The method is sensitive down to approximately 10 microg, exhibits good reproducibility and may be used as a preliminary step for the separation of individual molecular species of phosphatidylcholines by high-performance liquid chromatography.